A graft copolymer with thermoresponsive poly-2-isopropyl-2-oxazoline side chains and an aromatic polyester backbone containing aliphatic spacer –(CH2)4– was synthesized and studied using NMR, GPC, static and dynamic light scattering, and turbidimetry. The molar mass of the main and side chains, their length, as well as the number of side chains and the density of their grafting were determined. The conformation in aqueous solution was assessed. The behavior in water when heated over a wide range of concentrations and temperatures was studied. The phase separation temperatures and their dependence on concentration were obtained, and LCST = 50 °C was determined. Kinetic characteristics of equilibrium establishment in solution and the formation of supramolecular structures were analyzed. The influence of the spacer length and side chain length on the thermoresponsiveness and self-organization of copolymer macromolecules was discussed. It was shown that, due to the long side chains and short distance between grafting points, phase separation upon heating is preceded by intramolecular aggregation.

Thermosensitive star-shaped poly-N-acyl-1,3-propylenimines with a macrocyclic trianglamine core were synthesized using a 'grafting-on' approach involving polymerization of 2-alkyl5,6-dihydro-4H-oxazines at free trianglamine. The resulting polymers form complexes with europium ions and curcumin and can be used in the creation of delivery systems for drugs as well as contrast agents for NMR tomography.

A new approach to the synthesis of polyrotaxanes from the polyethylenimine‒block‒poly(ethylene glycol)‒block‒polyethylenimine copolymer and alpha-cyclodextrin has been proposed. It has been shown that the acylation of free amino groups of polypseudorotaxane effectively blocks decomposition of the complex in solution. The structure of the synthesized copolymers has been studied in detail by 1Н and 13С NMR spectroscopy, IR analysis, and GPC. It is assumed that the observed abnormally high optical activity of the resulting rotaxanes is probably associated with the formation of chiral helical supramolecular structures.

Thermosensitivestar-shapedpoly-N-acyl-1,3-propylenimines with a macrocyclic trianglamine core were synthesized using a ‘grafting-on’ approach involving polymerization of 2-alkyl-5,6-dihydro-4H-oxazines at free trianglamine. The resulting polymers form complexes with europium ions and curcumin and can be used in the creation of delivery systems for drugs as well as contrast agents for NMR tomography.

Polyrotaxanes with poly-2-alkyl-2-oxazoline blocking moieties have been successfully synthesized. The structure of the synthesized samples was confirmed by NMR spectroscopy, and the molar masses were measured by light scattering and GPC. The density of cyclodextrin rings on polyethylene glycol did not depend on the structure of poly-2-alkyl-2-oxazoline chains and ranged from 2 to 5. A high specific optical rotation of the prepared polyrotaxanes is found which is caused by the formation of hydrogen bonds between neighboring macrocycles. The behavior of water-salt solutions of synthesized polyrotaxanes depended on the size of the poly-2-alkyl-2oxazoline side groups. Only polymers with poly-2-isopropyl-2-oxazoline and poly-2-n-propyl-2-oxazoline blocking moieties were thermoresponsive in aqueous solutions, and the phase separation temperature decreased at passage from a polymer with poly-2-isopropyl-2-oxazoline to a sample with poly-2-n-propyl-2-oxazoline. Aqueous solutions of polyrotaxanes with smaller side groups were molecularly dispersed at all temperatures, and the polymer with poly-2-butyl-2-oxazoline blocking chains did not dissolve in water.

A novel grafting-onto approach was applied to the synthesis of star-shaped poly(2-alkyl-2-oxazoline)s with macrocyclic calix[4]arene core. Cationic polymerizations of 2-ethyl-2-oxazoline and 2-isopropyl-2-oxazoline were terminated using calix[4]arene tetrahydrazide as a multifunctional termination agent. Molecular-weight and structural characteristics of obtained four-arm star poly(2-alkyl-2-oxazoline)s were determined by size exclusion chromatography and light scattering. The thermosensitivity of aqueous solutions of obtained star polymers was studied. Cloud points, determined for 1% wt. aqueous solutions were equal to tcp50% = 27.5 degrees C for CA4-PiPrOx and tcp50% = 73.1 degrees C for CA4-PEtOx. Critical micelle concentrations of aqueous solutions of star polymers were determined using UV-Vis absorption spectroscopy, they were equal to 2.20 x 10-4 g/mL for CA4-PEtOx and 1.68 x 10-4 g/mL for CA4-PiPrOx. It was shown that studied poly(2-alkyl-2-oxazoline)s form water-soluble complexes with hydrophobic curcumin. The composition of curcumin-polymer complexes and their stability in aqueous solutions were studied using UV-Vis absorption spectroscopy. Obtained Job's plots indicated the formation of bimolecular curcumin-polymer complexes. Binding constants of curcumin by studied calixarene-centered star polymers were equal to (5-7)x 104 L/mol.

Functional polyrotaxanes of N-alkanoylpolyethyleneimine@ α-cyclodextrin type are synthesized by acylation of the polypseudorotaxane precursor, namely, a polyethylenimine@ α-cyclodextrin inclusion complex, with excess of carboxylic acid anhydrides. In the course of the processing, α-cyclo-dextrin moieties are also fully O-acylated. The introduction of acyl moieties into polyethyleneimine backbone prevents the expulsion of α-cyclodextrin rings from this backbone.

Regular and irregular molecular brushes with polydimethylsiloxane backbone and poly-2-isopropyl-2-oxazoline side chains have been synthesized. Prepared samples differed strongly in the side chain grafting density, namely, in the ratio of the lengths of spacer between the grafting points and the side chains. The hydrodynamic properties and molecular conformation of the synthesized grafted copolymers and their behavior in aqueous solutions on heating were studied by the methods of molecular hydrodynamics and optics. It was found that the regularity and the grafting density do not affect the molecular shape of the studied samples of molecular brushes in the selective solvent. On the contrary, the grafting density is one of the most important factors determining the thermoresponsivity of grafted copolymers. It was shown that in analyzing self-organization and LCST values in aqueous solutions of poly-2-isopropyl-2-oxazolines with complex architecture, many factors should be considered. First is the molar fraction of the hydrophobic fragment and the intramolecular density. It was found that molar mass is not a factor that greatly affects the phase transition temperature of poly-2-isopropyl-2-oxazolines solutions at a passage from one molecular architecture to another.

A new approach to the synthesis of thermoresponsive polyrotaxanes, which is based on the termination of poly(2-ethyl-2-oxazoline) living chains by the end groups of polypseudorotaxane obtained from α,ω-diamino poly(ethylene glycol) 2000 and α-cyclodextrin, is proposed. It is shown that poly(2-ethyl-2-oxazoline) synthesized by cationic ring-opening polymerization interacts with polypseudorotaxane end groups and thus effectively blocks dissociation of the complex in solution. The structure of the synthesized copolymers is characterized in detail by 1Н and 13С spectroscopy, IR analysis, and GPC. It is demonstrated that the aqueous solutions of the synthesized polymers feature the lower critical solution temperature.

A polycondensation aromatic polyester with an oxygen spacer was synthesized and used as a macroinitiator for the grafting of linear poly(2-isopropyl-2-oxazoline) (PiPrOx) by the cationic polymerization method. The length of the thermosensitive side chains was varied by the initiator:monomer ratio. Using methods of molecular hydrodynamics, light scattering and turbidimetry, the copolymers were studied in organic solvents and in water. The molecular characteristics of the main chain and graft copolymers, the polymerization degree of side chains and their grafting density have been determined. The equilibrium rigidity of the macroinitiator and the conformations of grafted macromolecules were evaluated. In selective solvents, they take on a star-like conformation or aggregate depending on the degree of shielding of the main chain by side chains. The thermoresponsiveness of graft copolymers in aqueous solutions was studied, and their LCST were estimated. The results are compared with data for graft copolymers composed of PiPrOx side chains and flexible or rigid chain backbones of aromatic polyester type.

A novel grafting-onto approach was applied to the synthesis of star-shaped poly(2-alkyl-2-oxazoline)s with macrocyclic calix[4]arene core. Cationic polymerization of 2-alkyl-2-oxazoline was terminated using calix[4]arene tetrahydrazide as a multifunctional termination agent. Molecular-weight and structural characteristics of obtained four-arm star poly(2-alkyl-2-oxazoline)s were determined by size exclusion chromatography and light scattering. The thermosensitivity of aqueous solutions of obtained star polymers was studied. Critical micelle concentrations of aqueous solutions of star polymers were determined using UV-Vis absorption spectroscopy. It was shown that star-shaped poly(2-alkyl-2-oxazoline)s with calix[4]arene branching center form water-soluble complexes with hydrophobic curcumin. The composition of obtained polymer complexes and their stability in aqueous solutions were studied.

New polymer brushes with an ester backbone and poly(methyl methacrylate) side chains are synthesized by polycondensation and polymerization methods. The initiating groups are sulfonyl chloride groups laterally attached to the polyester chain. PMMA side chains are grafted by the ATRP method according to the "grafting from" multicenter macroinitiator strategy. The conditions for the polymerization processes in a controlled mode are selected, and the ways of targeted regulation of the degree of polymerization of methacrylate side chains are determined. Using the synthesized copolymers self-supporting films are obtained, and their physical and mechanical properties are studied.

The synthesis of polyamides containing lateral sulfonyl chloride groups is proposed. The presented polymers can serve as macroinitiators for preparing thermosensitive polyoxazolines. It is proved that polymerization with multisulfochloride initiators proceeds without irreversible termination reaction and makes it possible to obtain polymers with a fairly narrow molecular weight distribution.

The cross-linked poly-2-isopropyl-2-oxazolines (PiPrOx) differing in cross-linker content have been synthesized and characterized by light scattering, chromatography, and rheometry. The dramatic influence of the cross-linker content on solubility and uni- or bimodality was observed. For the first time, the interpolymer complex of cross-linked PiPrOx with polyethylene oxide is manufactured in fibrous form by the electrospinning method. The role of intermolecular hydrogen bonds in the structure and properties of electrospun fibers (EF) was studied by infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. It was established that these interactions allow to obtain a uniform fibrous membrane. At the same time, hydrogen bonding is responsible for the self-organization of PiPrOx in water.

Linear and star-shaped poly(2-ethyl-2-oxazine)s have been synthesized. The star core was a calix[4]arene. The linear polymers and star arms were prepared by the cationic ring-opening polymerization of 2-ethyl-2-oxazine. The grafting-onto approach was used to synthesize the polymer stars. Molar masses were in the range from 2500 to 38,000 g center dot mol- 1 for linear samples and from 5100 to 23,000 g center dot mol- 1 for stars. Hydrodynamic and conformational behavior of synthesized polymers were investigated by molecular hydrodynamics and optics methods in dilute solutions in 2-nitropropane. It was shown that linear poly(2-ethyl-2-oxazine) is a flexible-chain polymer with length of statistical Kuhn segment 1.5 nm and macromolecular diameter 0.5 nm. The molecules of starshaped poly(2-ethyl-2-oxazine) are characterized by compact structure and high intramolecular density. The arms are coiled to shield the calix[4]arene core from the solvent. The arm lengthening leads to a decrease in the intramolecular density and shape symmetry of the star-shaped molecules.

Star-shaped polymers with the calix[8]arene core and poly(2-isopropyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline)–poly[3-(2-oxazoline)propionic acid] block copolymer arms at various ways of attaching blocks to the core are synthesized by ring-opening cationic polymerization. Luminescent labels are introduced by the esterification of carboxyl groups by diazomethane derivatives. In order to obtain interpolymer complexes luminescently labeled poly(methacrylic acid) and poly(acrylic acid) are synthesized. The resulting polymers are characterized by the methods of molecular hydrodynamics and optics. Interpolymer complex formation in the aqueous solutions of the polymers is studied by polarized luminescence. It is shown that the chemical structure of the polyoxazoline fragment and the way of its addition to the core influence the structural and dynamic characteristics of the interpolymer complexes with polycarboxylic acids and their stability.

A new polycondensation aromatic rigid-chain polyester macroinitiator was synthesized and used to graft linear poly-2-ethyl-2-oxazoline as well as poly-2-isopropyl-2-oxazoline by cationic polymerization. The prepared copolymers and the macroinitiator were characterized by NMR, GPC, AFM, turbidimetry, static, and dynamic light scattering. The molar masses of the polyester main chain and the grafted copolymers with poly-2-ethyl-2-oxazoline and poly-2-isopropyl-2-oxazoline side chains were 26,500, 208,000, and 67,900, respectively. The molar masses of the side chains of poly-2-ethyl-2-oxazoline and poly-2-isopropyl-2-oxazoline and their grafting densities were 7400 and 3400 and 0.53 and 0.27, respectively. In chloroform, the copolymers conformation can be considered as a cylinder wormlike chain, the diameter of which depends on the side chain length. In water at low temperatures, the macromolecules of the poly-2-ethyl-2-oxazoline copolymer assume a wormlike conformation because their backbones are well shielded by side chains, whereas the copolymer with short side chains and low grafting density strongly aggregates, which was visualized by AFM. The phase separation temperatures of the copolymers were lower than those of linear analogs of the side chains and decreased with the concentration for both samples. The LCST were estimated to be around 45 °C for the poly-2-ethyl-2-oxazoline graft copolymer, and below 20 °C for the poly-2-isopropyl-2-oxazoline graft copolymer.